Package delivery companies pick up millions of packages daily from thousands of locations over a large geographical area and transport them, primarily by truck and airplane, to a correspondingly large number of scattered destinations. To meet a rigorous schedule and provide accurate deliveries, a package delivery company must use automated transfer systems to match incoming packages with proper outgoing transport headed for the packages' destinations. Because deliveries are time sensitive, the sorting equipment must be very fast, yet provide gentle and accurate handling of packages.
Meeting this goal is particularly difficult in the case of large or heavy packages. Some package delivery companies severely restrict the maximum size of packages they will accept for delivery, but United Parcel Service, the assignee of the present application, accepts a wide range of package sizes, shapes and weights.
Belt and roller conveyor systems have often been used in package sorting systems to move packages from incoming loading docks to outgoing transport. An initial sorting of packages traveling along a conveyor may be accomplished by diverting packages from the conveyor based on their destinations, or based on their size or another characteristic.
To automate handling of articles in conveyor systems, conveyor diverter assemblies of various types have been developed. Roller bed diverters using right angle transfer belts are shown in U.S. Pat. No. 4,798,275 to Leemkuil et. al., and U.S. Pat. No. 4,174,774 to Bourgeois. These systems have a relatively large number of moving parts, and repair would be expected to be complex and time consuming.
U.S. Pat. No. 3,926,298, provides a main conveyor having multiple powered wheels, and a diagonal belt conveyor fitted between the wheels below the normal conveyor surface. A section of the drive rollers can be lowered to drop a parcel onto the belt conveyor, without interrupting the speed of articles moving along the primary path. However, the belt conveyor can divert in only one direction.
U.S. Pat. No. 5,547,084 shows a luggage sorting system in which bags are fed onto a moving carriage that includes multiple conveyors. After loading, the carriage moves along a track until it aligns with output conveyors. Then the carriage conveyors shift the bags from the carriage to appropriate output conveyors. This is not a high speed sorting system because the bags must come to rest on the carriage and be transported laterally, and then accelerated again after sorting.
Thus, there is a need in the art for a diverter that can reliably divert large packages from a main conveyor path, using a non-complex mechanism that is modular and easy to repair, all while operating at a high speed of throughput along the main path.